Materials capable of polarizing light have been commercially available for many years. The best known application is in the ophthalmic area, namely, sunglasses. It is common practice to produce a polarizing element by dispersing a second phase in an organic plastic matrix. The plastic element might be adhered to, or sandwiched between, glass elements to provide scratch resistance.
Many optical instruments embody an optical train, that is a plurality of components. Frequently, such a train requires means for polarizing light rays, referred to as a polarizer, and also means for modifying or altering the light rays, such as a lens or mirror. The components in an optical train may be completely separate elements mechanically arranged or mounted in an operating instrument or system. Such a system tends to be bulky and inconvenient to use.
Alternatively, the components may be bonded or adhered together. For example, a layer of polarizing plastic material may be adhesively bonded to a glass lens. In such an arrangement, chemical durability and delamination problems may be encountered, particularly if the composite is exposed to temperature extremes and/or high humidity. Organic materials, whether employed as a component or as an adhesive, cannot, of course, withstand elevated temperatures.
In summary, there is currently no integral, that is single body, polarizing lens, either in glass or in plastic. Rather, it is common practice to fabricate a lens from either organic or glass material. Then a layer of polarizing plastic is bonded to a surface of the lens.
It has been recognized that various advantages would accrue from an integral structure. These include,
a. An integral body could be more compact, and hence easier to handle and use. PA1 b. Problems of delamination and chemical durability would be avoided. PA1 c. Multiple interfaces having differing refractive indices, whereby light is lost during transmission, would be reduced.
It is therefore a primary purpose of the present invention to provide an integral body that will deliver both polarizing and light altering properties. Another purpose is to provide an integral body embodying both a polarizer and a light altering element, such as a lens or mirror. A further purpose is to provide an optical system or instrument incorporating such an integral body.